Release 10.1A: OpenEdge Getting Started:
Database Essentials

Tunable operating system resources

The OpenEdge RDBMS relies on operating system resources, such as the file system and processes, to perform its operations. The following resources directly impact the performance of your database:

Semaphores — Semaphores are operating system constructs that act as resource counters. The database engine uses semaphores to synchronize the interprocess activities of server and self-service client processes that are connected to a database. By default, each database has an array of semaphores, one for each user or server. Each process uses its semaphore when it must wait for a shared resource. Semaphores are not used for single-user sessions. The Semaphore sets (-semsets) startup parameter allows you to change the number of semaphore sets available to the broker. You might also need to set some kernel or system parameters to increase the number of semaphores.
File descriptors — A file descriptor is an identifier assigned to a file when it is opened. There is a system limit on the number of file descriptors. Each database process (clients, remote client servers, and the broker) uses several file descriptors for both database files and application files. You might have to adjust the system file descriptor limit.
Processes — Brokers, servers, clients, and background writers run as processes. Processes implement the client, the server, or the functions for both on a node. Processes also coordinate communication among nodes and provide operating system and application services for the node. A kernel or system parameter in the operating system limits the number of active processes that can run on a system. You might have to raise the parameter to allow for more processes.
Shared Memory — Shared memory is an area in system memory that multiple users can access concurrently. You might have to adjust the maximum shared-memory segment size and the total number of available segments to improve system performance.

For information on setting kernel and system parameters, see your operating system documentation.